Chemical abundances and winds of massive stars in M31: a Btype
... versus 0.3 for HD 92809). Our study represents the first detailed, chemical model atmosphere analysis for either a B-type supergiant or a Wolf –Rayet (WR) star in Andromeda, and shows the potential of how such studies can provide new information on the chemical evolution of galaxies and the evolutio ...
... versus 0.3 for HD 92809). Our study represents the first detailed, chemical model atmosphere analysis for either a B-type supergiant or a Wolf –Rayet (WR) star in Andromeda, and shows the potential of how such studies can provide new information on the chemical evolution of galaxies and the evolutio ...
Science with the Constellation
... Universe. Today we are confident that their ultimate power source is the release of gravitational energy sustained by an accretion disk, which is feeding matter directly into a central supermassive black hole. Such black holes appear to reside at the centers of most galaxies, and they have masses of ...
... Universe. Today we are confident that their ultimate power source is the release of gravitational energy sustained by an accretion disk, which is feeding matter directly into a central supermassive black hole. Such black holes appear to reside at the centers of most galaxies, and they have masses of ...
Galaxies
... increase in wavelength Redshifts are measured directly Distances are calculated from them using Hubble’s constant, which is uncertain ...
... increase in wavelength Redshifts are measured directly Distances are calculated from them using Hubble’s constant, which is uncertain ...
Carbon-enhanced metal-poor stars in dwarf galaxies
... theoretical predictions are consistent with recent observations of star formation histories in ultra-faint dwarf galaxies (e.g. Dall’Ora et al. 2012; Okamoto et al. 2012; Brown et al. 2012, 2014). In particular, by interpreting the observed FeLuminosity relation and metallicity distribution function ...
... theoretical predictions are consistent with recent observations of star formation histories in ultra-faint dwarf galaxies (e.g. Dall’Ora et al. 2012; Okamoto et al. 2012; Brown et al. 2012, 2014). In particular, by interpreting the observed FeLuminosity relation and metallicity distribution function ...
Chemical abundances and winds of massive stars in M31: a B
... Numerous surveys have identified OB and WR stars beyond the Magellanic Clouds e.g. Massey et al. (1986); Moffat & Shara (1987), although little quantitative analysis has been carried out to date. The only detailed studies of WolfRayet stars beyond the Magellanic Clouds have been studies of late WN s ...
... Numerous surveys have identified OB and WR stars beyond the Magellanic Clouds e.g. Massey et al. (1986); Moffat & Shara (1987), although little quantitative analysis has been carried out to date. The only detailed studies of WolfRayet stars beyond the Magellanic Clouds have been studies of late WN s ...
Quiescent and flaring X-ray emission from the nearby M/T dwarf
... Magnetic activity phenomena in the outer atmospheric layers of late-type, very low mass stars are remarkable, since these stars are generally assumed to be fully convective, so that a solartype dynamo is not expected to operate. Furthermore, their cool atmospheres (T eff 2500 K) should be virtually ...
... Magnetic activity phenomena in the outer atmospheric layers of late-type, very low mass stars are remarkable, since these stars are generally assumed to be fully convective, so that a solartype dynamo is not expected to operate. Furthermore, their cool atmospheres (T eff 2500 K) should be virtually ...
Dynamical properties of a large young disk galaxy at z=2.03⋆
... with the local stellar mass TFR. F257 is then a nearly (∼ 75%) maximum disk. The dynamical properties of F257 are more like those of local galaxies than those of any other galaxy at similar redshift observed to date. However, the gas-to-stellar mass ratio is unusally large: 2.5. Key words. Galaxies: ...
... with the local stellar mass TFR. F257 is then a nearly (∼ 75%) maximum disk. The dynamical properties of F257 are more like those of local galaxies than those of any other galaxy at similar redshift observed to date. However, the gas-to-stellar mass ratio is unusally large: 2.5. Key words. Galaxies: ...
Measuring distances to the edge of the local group
... estimating the size of a galaxy based on its rotational velocity, but changed at certain mass limits. Was this caused by an underlying physical phenomenon that we did not understand the mechanics of? Or was it potentially a problem with our measuring techniques? Noordermeer & Verheijen (2007) took a ...
... estimating the size of a galaxy based on its rotational velocity, but changed at certain mass limits. Was this caused by an underlying physical phenomenon that we did not understand the mechanics of? Or was it potentially a problem with our measuring techniques? Noordermeer & Verheijen (2007) took a ...
distance
... • How can we start to understand them? (lessons learned from stars about this?) – measure properties • If you know distance and you measure flux you can figure out total luminosity • Distance measurements that work to other galaxies: Cepheids — BRIGHT! Can see them out to ~40 Mpc ...
... • How can we start to understand them? (lessons learned from stars about this?) – measure properties • If you know distance and you measure flux you can figure out total luminosity • Distance measurements that work to other galaxies: Cepheids — BRIGHT! Can see them out to ~40 Mpc ...
Astronomical Picture of the Day
... galaxies Abell 1185. There at least two galaxies, cataloged as Arp 105 and dubbed The Guitar for their familiar appearance, are pulling each other apart gravitationally. Most of Abell 1185's hundreds of galaxies are elliptical galaxies, although spiral, lenticular, and irregular galaxies are all cle ...
... galaxies Abell 1185. There at least two galaxies, cataloged as Arp 105 and dubbed The Guitar for their familiar appearance, are pulling each other apart gravitationally. Most of Abell 1185's hundreds of galaxies are elliptical galaxies, although spiral, lenticular, and irregular galaxies are all cle ...
Teil 2
... orbital motion, i.e., they appear centred at the central meridian during the respective quadrature phases, thus are not facing each other as would be the case for a hypothetical reflection effect. The leading hemispheres on both components appear with an effectively lower temperature than the traili ...
... orbital motion, i.e., they appear centred at the central meridian during the respective quadrature phases, thus are not facing each other as would be the case for a hypothetical reflection effect. The leading hemispheres on both components appear with an effectively lower temperature than the traili ...
Chandra Characterization of X-ray Emission in the Young F
... total mass, they are a natural testbed for trying to understand the mechanisms of exosystem formation. As Myr-old F-stars can be expected to be fast rotators, and more convective and X-ray active than their main sequence cousins, we would have naively expected both stars to be rapidly rotating, high ...
... total mass, they are a natural testbed for trying to understand the mechanisms of exosystem formation. As Myr-old F-stars can be expected to be fast rotators, and more convective and X-ray active than their main sequence cousins, we would have naively expected both stars to be rapidly rotating, high ...
Article PDF - IOPscience
... obscuration unresolved in the HST optical images could hide the accreting gas. Mid-IR observations should detect this gas if it exists, which may provide strong supporting evidence for accretion flows leading to AGN outbursts in CSOs. Observations like the HST imaging and the mid-IR results presente ...
... obscuration unresolved in the HST optical images could hide the accreting gas. Mid-IR observations should detect this gas if it exists, which may provide strong supporting evidence for accretion flows leading to AGN outbursts in CSOs. Observations like the HST imaging and the mid-IR results presente ...
– 1 – 1. Galaxy Observations 1.1.
... rate affecting the UV continuum, and the calibration for UV stellar photospheric features or UV ISM absorption to metallicity is not well understood at present (see Erb 2010 for details). So the best approach is to move into the near-IR, where the normal optical low redshift techniques and calibrati ...
... rate affecting the UV continuum, and the calibration for UV stellar photospheric features or UV ISM absorption to metallicity is not well understood at present (see Erb 2010 for details). So the best approach is to move into the near-IR, where the normal optical low redshift techniques and calibrati ...
The science case for - Astrophysics
... photons which re-ionised the Universe some 200million years after the Big Bang, and made it transparent? These objects may be visible through their supernovae, or their ionisation zones. How many types of matter exist? What is dark matter? Where is it? Most matter is transparent, and is detectable o ...
... photons which re-ionised the Universe some 200million years after the Big Bang, and made it transparent? These objects may be visible through their supernovae, or their ionisation zones. How many types of matter exist? What is dark matter? Where is it? Most matter is transparent, and is detectable o ...
in BRIGHTEST STARS
... Deneb (bottom half of frame) is 200 times bigger than the sun. Image via AstroBob In order for us to see it at its enormous distance, Deneb must also be tremendously bright and energetic. Among the 20 brightest stars, only Rigel in Orion surpasses Deneb in intrinsic brightness. Deneb is an A2Ia star ...
... Deneb (bottom half of frame) is 200 times bigger than the sun. Image via AstroBob In order for us to see it at its enormous distance, Deneb must also be tremendously bright and energetic. Among the 20 brightest stars, only Rigel in Orion surpasses Deneb in intrinsic brightness. Deneb is an A2Ia star ...
Measurements of Neutron Star Masses
... 2 This way, TEMPO settles 2 on a DM 1 for 2this any given epoch. day that produces the best overall fit. This can bring to light intrinsic DM variations, but it can also absorb other frequency dependent effects. On two days, outliers suggest instrument 1 Figs. 9 and 10), and these problems (MJDs 535 ...
... 2 This way, TEMPO settles 2 on a DM 1 for 2this any given epoch. day that produces the best overall fit. This can bring to light intrinsic DM variations, but it can also absorb other frequency dependent effects. On two days, outliers suggest instrument 1 Figs. 9 and 10), and these problems (MJDs 535 ...
SUB-KILOPARSEC IMAGING OF COOL MOLECULAR GAS IN
... dust both in the local universe and at high redshift in order to understand the physics and history of star formation. One of the most studied correlations is the powerlaw relationship between the gas surface density, Σgas , and the SFR surface density, ΣSFR (Schmidt 1959; Kennicutt 1998; see Kennic ...
... dust both in the local universe and at high redshift in order to understand the physics and history of star formation. One of the most studied correlations is the powerlaw relationship between the gas surface density, Σgas , and the SFR surface density, ΣSFR (Schmidt 1959; Kennicutt 1998; see Kennic ...
PPT presentation
... Ciardullo, Jacoby & Ford (1989b) detected 249 PNe in three Leo I early type galaxies: NGC 3377 (E6), NGC 3379 (E0) and NGC 3384 (S0). All had similar PN [O III] luminosity functions, indistinguishable from those observed in the spiral galaxies M31 and M81. The invariance with galaxy type and metall ...
... Ciardullo, Jacoby & Ford (1989b) detected 249 PNe in three Leo I early type galaxies: NGC 3377 (E6), NGC 3379 (E0) and NGC 3384 (S0). All had similar PN [O III] luminosity functions, indistinguishable from those observed in the spiral galaxies M31 and M81. The invariance with galaxy type and metall ...
Full-text PDF
... recipes, parameterised formulae which encapsulate ‘subgrid’ physics in terms of star formation thresholds, Schmidt ‘laws’ for star formation, Bondi models for black hole feeding, etc. The form and the parameters of these recipes are chosen to reproduce the observed systematics of star formation and ...
... recipes, parameterised formulae which encapsulate ‘subgrid’ physics in terms of star formation thresholds, Schmidt ‘laws’ for star formation, Bondi models for black hole feeding, etc. The form and the parameters of these recipes are chosen to reproduce the observed systematics of star formation and ...
Hubble Space Telescope Imaging of Post
... massive systems showing activity (Heckman et al. 2004). Thus, as we move from quasar to Seyfert luminosities, fueling rates and triggering mechanisms may differ (Hopkins & Hernquist 2009). For example, bars in spiral galaxies may be sufficient to fuel such nuclear activity. For this reason, and sinc ...
... massive systems showing activity (Heckman et al. 2004). Thus, as we move from quasar to Seyfert luminosities, fueling rates and triggering mechanisms may differ (Hopkins & Hernquist 2009). For example, bars in spiral galaxies may be sufficient to fuel such nuclear activity. For this reason, and sinc ...
Building galaxies Hunt, Leslie Kipp
... “S0’s”, a class of galaxies roughly intermediate between ellipticals and early-type Sa spirals, but with a variety of appearances because of the presence or absence of dust lanes (Sandage 1961). They lack spiral arms but, unlike ellipticals, contain a low-surface brightness envelope surrounding the ...
... “S0’s”, a class of galaxies roughly intermediate between ellipticals and early-type Sa spirals, but with a variety of appearances because of the presence or absence of dust lanes (Sandage 1961). They lack spiral arms but, unlike ellipticals, contain a low-surface brightness envelope surrounding the ...
The environment of high-redshift AGN OLIMPIA JUDIT FOGASY
... According to the currently accepted cosmological model, the Λ Cold Dark Matter model (ΛCDM), structure formation started from primordial density fluctuations followed by gravitational collapse of dark matter, leading to the formation of dark matter haloes. As the virial equilibrium is reached in the ...
... According to the currently accepted cosmological model, the Λ Cold Dark Matter model (ΛCDM), structure formation started from primordial density fluctuations followed by gravitational collapse of dark matter, leading to the formation of dark matter haloes. As the virial equilibrium is reached in the ...
Determination of the distance to the Andromeda Galaxy using variable stars U
... A.1 The observed phenomenon Flares are observed on magnetically active stars and, much more closely, on the Sun. Electromagnetic radiation is emitted across the entire spectrum, from radio waves through the optical range to X-rays and γ-rays. The total energy released during a typical solar flare is ...
... A.1 The observed phenomenon Flares are observed on magnetically active stars and, much more closely, on the Sun. Electromagnetic radiation is emitted across the entire spectrum, from radio waves through the optical range to X-rays and γ-rays. The total energy released during a typical solar flare is ...
Gamma-ray burst
Gamma-ray bursts (GRBs) are flashes of gamma rays associated with extremely energetic explosions that have been observed in distant galaxies. They are the brightest electromagnetic events known to occur in the universe. Bursts can last from ten milliseconds to several hours. The initial burst is usually followed by a longer-lived ""afterglow"" emitted at longer wavelengths (X-ray, ultraviolet, optical, infrared, microwave and radio).Most observed GRBs are believed to consist of a narrow beam of intense radiation released during a supernova or hypernova as a rapidly rotating, high-mass star collapses to form a neutron star, quark star, or black hole. A subclass of GRBs (the ""short"" bursts) appear to originate from a different process – this may be due to the merger of binary neutron stars. The cause of the precursor burst observed in some of these short events may be due to the development of a resonance between the crust and core of such stars as a result of the massive tidal forces experienced in the seconds leading up to their collision, causing the entire crust of the star to shatter.The sources of most GRBs are billions of light years away from Earth, implying that the explosions are both extremely energetic (a typical burst releases as much energy in a few seconds as the Sun will in its entire 10-billion-year lifetime) and extremely rare (a few per galaxy per million years). All observed GRBs have originated from outside the Milky Way galaxy, although a related class of phenomena, soft gamma repeater flares, are associated with magnetars within the Milky Way. It has been hypothesized that a gamma-ray burst in the Milky Way, pointing directly towards the Earth, could cause a mass extinction event.GRBs were first detected in 1967 by the Vela satellites, a series of satellites designed to detect covert nuclear weapons tests. Hundreds of theoretical models were proposed to explain these bursts in the years following their discovery, such as collisions between comets and neutron stars. Little information was available to verify these models until the 1997 detection of the first X-ray and optical afterglows and direct measurement of their redshifts using optical spectroscopy, and thus their distances and energy outputs. These discoveries, and subsequent studies of the galaxies and supernovae associated with the bursts, clarified the distance and luminosity of GRBs. These facts definitively placed them in distant galaxies and also connected long GRBs with the explosion of massive stars, the only possible source for the energy outputs observed.